scholarly journals Modeling acoustic wave propagation and reverberation in an ice covered environment using finite element analysis

2018 ◽  
Author(s):  
Blake Simon ◽  
Marcia Isakson ◽  
Megan Ballard
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Wave Propagation ◽  
Acoustic Wave ◽  
Acoustic Wave Propagation ◽  
Element Analysis

scholarly journals Acoustic Wave Propagation in Air-Filled Pipes Using Finite Element Analysis

2018 ◽  
Vol 8 (8) ◽  
pp. 1318 ◽  
Author(s):  
Mustapha Abdullahi ◽  
S Oyadiji
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Wave Propagation ◽  
Acoustic Wave ◽  
Wave Velocity ◽  
Acoustic Wave Propagation ◽  
Element Analysis ◽  
Hexahedral Elements ◽  
Element Type ◽  
3D Solid

The major objective of this work is to develop an efficient Finite Element Analysis (FEA) procedure to simulate wave propagation in air-filled pipes accurately. The development of such a simulation technique is essential in the study of wave propagation in pipe networks such as oil and gas pipelines and urban water distribution networks. While numerical analysis using FEA seems superficially straight forward, this paper demonstrates that the element type and refinement used for acoustic FEA have a significant effect on the accuracy of the result achieved and the efficiency of the computation. In particular, it is shown that the well-known, better overall performance achieved with 3D solid hexahedral elements in comparison with 2D-type elements in most stress and thermal applications does not occur with acoustic analysis. In this paper, FEA models were developed taking into account the influence of element type and sizes using 2D-like and 3D element formulations, as well as linear and quadratic nodal interpolations. Different mesh sizes, ranging from large to very small acoustic wavelengths, were considered. The simulation scheme was verified using the Time of Flight approach to derive the predicted acoustic wave velocity which was compared with the true acoustic wave velocity, based on the input bulk modulus and density of air. For finite element sizes of the same order as acoustic wavelengths which correspond to acoustic frequencies between 1 kHz and 1 MHz, the errors associated with the predictions based on the 3D solid hexahedral acoustic elements were mostly greater than 15%. However, for the same element sizes, the errors associated with the predictions based on the 2D-like axisymmetric solid acoustic elements were mostly less than 2%. This indicates that the 2D-like axisymmetric solid acoustic elements are much more efficient than the 3D hexahedral acoustic elements in predicting acoustic wave propagation in air-filled pipes, as they give higher accuracies and are less computationally intensive. In most stress and thermal FEA, the 3D solid hexahedral elements are much more efficient than 2D-type elements. However, for acoustic FEA, the results show that 2D-like axisymmetric elements are much more efficient than 3D solid hexahedral elements.

Finite element analysis and experimental measurement of acoustic wave propagation for leakage detection in an air-filled pipe

2017 ◽  
Vol 8 (4) ◽  
pp. 452-467 ◽  
Author(s):  
Julius Owowo ◽  
S. Olutunde Oyadiji
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Wave Propagation ◽  
Acoustic Wave ◽  
Research Work ◽  
Leakage Detection ◽  
Acoustic Wave Propagation ◽  
Element Analysis ◽  
Content Type ◽  
First Time

Purpose The purpose of this paper is to employ the acoustic wave propagation method for leakage detection in pipes. The first objective is to use acoustic finite element analysis (AFEA) method to simulate acoustic wave propagation and acoustic wave reflectometry in an intact pipe and in pipes with leaks of various sizes. This is followed by the second objective which is to validate the effectiveness and the practicability of the acoustic wave method via experimental testing. The third objective involves the decomposition and de-noising of the measured acoustic waves using stationary wavelet transform (SWT). It is shown that this approach, which is used for the first time on leakage detection in pipes, can be used to identify, locate and estimate the size of a leakage defect in a pipe. Design/methodology/approach The research work was designed inline with best practices and acceptable standards. The research methodology focusses on five basic areas: literature review; experimental measurements; simulations; data analysis and writing-up of the study with clear-cut communication of the findings. The approach used was acoustic wave propagation-based method in conjunction with SWT for leakage detection in fluid-filled pipe. Findings First, the simulation of acoustic wave propagation and acoustic wave reflectometry in fluid-filled pipes with and without leakage have great potential in leakage detection in pipeline systems and can detect very small leaks of 1 mm diameter. Second, the measured noise-contaminated acoustic wave propagation in a fluid-filled pipe can be successfully de-noised using the SWT method in order to clearly identify and locate leakage as little as 5 mm diameter in a pipe. Third, AFEA of a fluid-filled pipe can be achieved with the simulation of only the fluid content of the pipe and without the inclusion of the pipe in the model. This eliminates contact interaction of the solid pipe walls and the fluid, and as a consequence reduces computational time and resources. Fourth, the relationship of the ratio of the leakage diameter to the ratio of the first and second secondary wave amplitudes caused by the leakage can be represented by a second-order polynomial function. Fifth, the identification of leakage in a pipe is intuitive from mere comparison of the acoustic waveforms of an intact pipe with that of a pipe with a leakage. Originality/value The research work is a novelty and was developed from the scratch. The AFEA of acoustic wave propagation and acoustic wave reflectometry in a static fluid-filled pipe, and the SWT method have been used for the first time to detect, locate and estimate the size of a leakage in a fluid-filled pipe.

Sign in / Sign up

Export Citation Format

Share Document